Propeller



July 5, 1927.

PROPELLER Filed JulylB, 1925 A. HARPER ET AL Patna Ja 1927. Y 1,634,616

UMTED STATES PATENT-OFFICE.

ALEXANDER HARPER AND STEWART ALEXANDER HARPER, OF DUNEDIN, OTAGO,

NEW ZEALAND. Z

PROPELLER.

Application filed July 18, 1925. Serial No. 44,533.

This invention relates to apparatus used hole being preferably taperedfrom the end for propelling vessels, and in particular to face 3 of the boss to produce a larger orifice the propulsion of sea-going vessels. I at the opposite end face 4 thereof; a key- The action of the marine propeller should way 5 to enable the boss 1 to be keyed to a force the water straight astern, and not suitable shaft is out along the hole 2, paralthrow it off the ends of the blades laterally, lcl with the axis of the said hole 2.

as occurs to a great extent with ordinary There are preferably two blades 6, which screw propellers. When a propeller of too are secured'by the part 7 to'the boss 1 by great a pitch is used, or in the case of a suitable means, or cast integral with it to three blade propeller of small diameter extend away from the said boss 1 in a directurning at high speed, churning is the retion almost parallel with the axis of he sult, and it is an established fact that a twohole 2 therein. The profile of the said blade blade propeller will procure a larger volume 6 is wavelike in form, the trough or concave of solid water when run at high speed than portion, 8 starting from the outside tip of 15 a three-blade propeller, which is apt to each blade, and extending in towards the churn, as there-is less chance of the water central revolving .axis of the two blades 6, passing through the blades freely. As a and in doing so forming a swell or convex propeller working in water performs exportion 10 throughout the entire length of actly as it does in the air, the only differeach blade. The diameter from tip to tips 20 ence being that in each case the propeller is 9 of each blade 6 may be referred to as the used in conjunction with a different element, major diameter, and the over-all distance there is no reason why it should not be used from 11 to 12 at the smaller end as the with equal merit on air vehicles. minor diameter of the propeller, the said The object of the invention is to provide wavelike formation extending for the enan improved propeller of the type herein tire length of each blade, and diminishing described and illustrated in the accompanyin wave-length towards the smaller end 5 ing drawings, having two or more blades, thereof. according to the size and purpose for which A propeller fashioned in accordance with 7 it is to be used for the more eflicientpropul my invention from sheet metal would in its sion of vessels than hitherto attained with blank form he in the shape ofa keystone,

the ordinary propeller, this being accornone end be ng much largerthan the other,

plished by using a propeller fashioned as or would appear like the section of a trunillustrated, the revolutions of the said procated cone; the sheet of metal would be cut peller being increased or/and reduced in along the broken lines 13, the metal encomvelocity in relation to the speed of the vespassed by the said broken lines 13 being dis-,

sel without undue loss of eificiency, this becarded, the edges 14 and 15 being bent round.

ing due principally to churning and slip exopposite to each other. The edges 16 and perienced with the ordinary propeller; 17 are then bent round so as to be opposite Referring to the drawings accompanying each other, and yet opposite in direction to 40 this specification, V I theirinnermost edgeslt and 15 respectively.

Figure 1 is a view of a propeller fash- The wave would then be formed in each ionedin accordance with my invention, the blade 6, the radius thereof reducing graduillustration showing. the said propeller in ally from the major diameter to the minor a vertical position with its boss uppermost, diameter and the waveformation becoming 45 Figure 2 is an elevation of Figure 1. less prominent. p

There is a boss 1, similar to that used 7 What we claim as new and desire to secure with an ordinary propeller, having a cenby Letters Patent is trally disposed hole 2 of suitable diameter A propeller of the character described, to fit a tail shaftor propeller shaft, the said including a shaft engaging boss, blades ex the blades being Wave-like in form and the inner marginal edges of each of the blades being bent 1n a Wave-like manner in a dlrection opposite the wavelike main portion of each blade, substantially as and for the purposes set forth. 10 In testimony whereof We have hereunto set our hands.

ALEXANDER HARPER. STEWART ALEXANQER HARPER. 

